Add AI job stage metrics

internal/store/store.go

@@ -674,7 +674,46 @@ ORDER BY owner_service, last_24h DESC, total DESC
 		}
 		out.Errors = append(out.Errors, stat)
 	}
-	return out, errorRows.Err()
+	if err := errorRows.Err(); err != nil {
+		return nil, err
+	}
+
+	stageRows, err := s.pool.Query(ctx, `
+SELECT owner_service,
+       task_type,
+       model_profile,
+       count(*) AS done_24h,
+       COALESCE(ROUND(AVG(EXTRACT(EPOCH FROM (completed_at - started_at))))::bigint, 0) AS avg_duration_seconds,
+       COALESCE(ROUND(AVG(attempts))::bigint, 0) AS avg_attempts,
+       count(*) FILTER (WHERE attempts > 1) AS retried_24h
+FROM ai_jobs
+WHERE status = 'done'
+  AND started_at IS NOT NULL
+  AND completed_at IS NOT NULL
+  AND completed_at > NOW() - INTERVAL '24 hours'
+GROUP BY owner_service, task_type, model_profile
+ORDER BY owner_service, task_type, model_profile
+`)
+	if err != nil {
+		return nil, err
+	}
+	defer stageRows.Close()
+	for stageRows.Next() {
+		var stat model.StageStat
+		if err := stageRows.Scan(
+			&stat.OwnerService,
+			&stat.TaskType,
+			&stat.ModelProfile,
+			&stat.Done24h,
+			&stat.AvgDurationSeconds,
+			&stat.AvgAttempts,
+			&stat.Retried24h,
+		); err != nil {
+			return nil, err
+		}
+		out.Stages = append(out.Stages, stat)
+	}
+	return out, stageRows.Err()
 }
 
 func scanJobSummary(row pgx.Row) (*model.JobSummary, error) {